The force is with those who read the source.
2016-02-25

Description

My friend keeps telling me, that real hackers speak assembly fluently. Are you a real hacker? Decode this string: “IVyN5U3X)ZUMYCs”
Attachment: rev50.zip

Exploit

As the title suggests, this is a MIPS assembly file (SPIM is a MIPS simulator). The key instruction is xor $a0,$a0, \$t1. This program uses a loop to xor every charactor with the counter. We can decode it as follw.

To solve this question, you either learn the basic of MIPS, or you can try xoring the first three charactors of encoded string IVy with the known beginning of th flag IW{. You will find out that the output is 0 1 2 and can guess the whole algorithm.

Flag: IW{M1P5_!S_FUN}